"Today, Valve will launch the beta of Big Picture mode, a version of Steam designed for your television. That's right. The de facto central hub of PC gaming is now designed to run while you're lounging in your living room - and with a controller, no less. I've tried out Big Picture. It's sleek, intuitive, and groundbreaking in several ways." We've talked about this before. If there's one company that can upend consoles, it's Valve. Everything is falling into place, and I wouldn't be surprised if this - what is essentially the software for the 'Steambox' - will have a tremendous effect on the games industry. Looks great, too.

Is MS' headstart really an advantage? Some folks hate Microsoft, and those who don't, don't exactly love it. Can't say that of Valve, never heard anyone hate Steam but lots that love 'em.
I believe they've got a better than fair chance.